Previously, any expressions inside destructuring patterns in a catch
would be parsed in the surrounding scope, instead of in the catch's
scope. This change fixes that by entering not only the catch scope,
but also the block scope inside it.

R=neis@chromium.org
BUG=v8:5106, v8:5112

Review-Url: https://codereview.chromium.org/2110193002
Cr-Commit-Position: refs/heads/master@{#37415}